1. Field of the Invention
The present invention relates to a shutter device which includes a first light-blocking unit that is movable between a charged position for closing a shutter aperture portion and a position for opening the shutter aperture portion; and a second light-blocking unit that is movable between a charged position for opening the shutter aperture portion and a position for closing the shutter aperture portion. The present invention also relates to an image-capturing apparatus equipped with a shutter device of this type.
2. Description of the Related Art
In a charged state of a typical shutter device of a direct-supporting type, an electromagnet corresponding to a first curtain included in the first light-blocking unit and an electromagnet corresponding to a second curtain included in the second light-blocking unit are electrified in order to maintain the first and second curtains in the charged state. By sequentially cutting off the electricity applied to the electromagnets, a light-exposure process is performed.
On the other hand, Japanese Patent Laid-Open No. 2001-215555 (corresponding to U.S. Pat. No. 6,850,281) discloses a shutter device in which driving levers for the second curtain and the first curtain are in a charged state when the charging operation of the shutter device is completed. This restores the second curtain to an image-capture preparation state such that the shutter device is set to an opened state. By performing a charge-releasing operation of the shutter device, the first curtain switches to an image-capture preparation state, whereby the shutter device is set to an image-capture preparation state.
According to the typical shutter device of the direct-supporting type described above, in order to maintain the opened-shutter state in which an image is viewable through, for example, a monitor provided on the back surface of a camera, it is necessary to keep electrifying the electromagnet that holds the second curtain. Consequently, this leads to an increase in power consumption.
In contrast, the shutter device disclosed in Japanese Patent Laid-Open No. 2001-215555 mechanically holds the first and second curtains, and drives the first and second curtains by unlocking a supporting mechanism. For this reason, it is not necessary to perform an electrical supporting operation for maintaining the second curtain. However, due to the fact that, for example, a second-curtain driving lever has a two-body structure, the shutter device requires a large number of components, which complicates the structure of the shutter device as well as leading to an expensive mechanism. Accordingly, further improvements can be made in a shutter device that holds the second curtain with a simple structure without needing to perform an electrical supporting operation for holding the second curtain.